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456

CANDLES

This residue may then be tested for cholesterol and for mineral and
resin oils in the way indicated on p. 388, in order to ascertain if the degras
contains wool fat, mineral oils and other unsaponifiable matters.

*

* *

Good degras is golden-yellow or orange and homogeneous and keeps well.

Natural degras usually contains 15-25% of water, while the artificial pro-
ducts contain 10-25%.

The other components may vary within the following limits, which are
referred to the dry degras (free from water) :

The non-fats (various organic residues) may reach 8% in natural degras
(ordinarily 2-5%), but are less than i% in artificial degras.

The ash may amount to 5% with natural degras, but is less than i% in
the artificial product; it should contain only traces of iron (not more than
0-05% of the original degras).

The free fatty acids, calculated as oleic acid, may vary from 20 to 30 % in
natural degras, but are usually less than 20% in the artificial ones.

The saponiftcation number is above 200 (220-240) in natural degras and
not less than 190 in artificial degras. A value less than 190 (referred to the
dry substance) denotes the presence of extraneous matter, such as mineral or
resin oils, vaseline or wool fat.

The proportion of degrag&ne is somewhat variable, since it depends on the
mode of preparation of the degras. Usually natural degras contains 6-20%
and the artificial product not more than 10% of degragdne.

The unsaponifiable matter does not exceed 3 % in pure degras, whether natural
or artificial, but is considerably higher in products adulterated with mineral
or resin oils, vaseline or wool fat.

CANDLES

Three types of candles are usually sold :  stearine, paraffin and wax.

Stearine candles, which are opaque and white, should be made from
stearine (mixture of stearic and palmitic acids, etc. ; see Stearine), but
very often they contain a certain quantity of paraffin wax (up to 50%)
and sometimes ceresine or a small quantity of carnauba wax (to raise the
melting point).

Paraffin candles, which are translucent and white, are made from paraffin
wax with a high melting point (about 50°), usually with the addition of
3-15% or even more (up to about 33%) of stearine, such being mixed or
composite candles.

Wax candles, which are yellowish and opaque and possess the charac-
teristic odour of wax, should be made from pure beeswax, but they are
nowadays usually made from mixtures of wax, paraffin wax, ceresine and
stearine, the wax being present often in small amount.

Analysis of candles is usually made with the object of determining the
composition, but includes also tests of the illuminating power and bending
properties.

1. Composition.—An idea of this is obtained firstly from the. objective
characters (see above). The composition is then determined qualitatively
and quantitatively by determinations of the solidifying point, of the acid,
saponification and iodine numbers, of the unsaponifiable substances and
the nature of the latter, the instructions laid down in the articles on stearine, This is the method proposed by the Committee for the analysis of degras at the